1. Field of the Invention
The present invention relates to a golf ball, more particularly to a golf ball having a paint film.
2. Description of the Related Art
A conventional golf ball has a paint film on the surface of the golf ball body. The paint film is formed to prevent the deterioration of the golf ball body due to the exposure of the sun light and the weather, as well as impart a gloss to the golf ball body, thereby improving the appearance thereof.
It is required for the paint film to have a durable adhesion against the impact, since the golf ball is repeatedly used and hit. Especially, since hitting the golf ball deforms the golf ball body, the paint film is likely to peel off in the case that the paint film covering the golf ball body does not follow the deformation of the golf ball body. In addition, the paint film may peel off when the golf ball is subject to the friction against the golf clubs when hitting the golf ball, and against the ground surfaces such as sand of bunker and rough when landing on the ground.
As a paint film of the golf ball, a polyurethane paint film is preferably used. For example, Japanese patent publication No. H11-146930 A discloses a polyurethane paint for the golf ball, which paint comprises a polyol containing a polyurethane polyol as a base resin and a polyisocyanate as a curing agent. Japanese patent No. 2573966 discloses a process for preparing a golf ball which process comprises coating a solution of ethyleneimine or a derivative of a carbodiimide to a golf ball having an ionomer resin cover, and then coating a polyurethane paint.
In recent years, it has been expected to reduce the usage of the solvent-borne paint in view of the environmental issues, and an aqueous paint has been studied to replace the solvent-borne paint used for the golf ball. For example, Japanese patent publication No. H08-71177 A discloses a golf ball where an aqueous polyurethane dispersion having a carboxyl group crosslinked with a carbodiimide compound is painted.